This is basically how a rail cannon coil gun works, just with electromagnets that can reverse their polarity.
It's a powerful way to accelerate anything — I think it's most famously used in those types of metal roller coasters that start you at a flat-with-the-ground angle, and then just fuckin launch you up a ramp to 45° with electromagnets. The issue is that you need a fuckton of energy to do that.
What we need for true perpetual energy is to just capture that guy Blanka from Street Fighter.